Mixing and emulsifying apparatus



y 3, 1966 u. PINTO 3,249,340

MIXING AND EMULSIFYING APPARATUS Filed June 20, 1960 3 Sheets-Sheet 2 l l I I I I I 1 y 3, 1966 u. PINTO 3,249,340

MIXING AND EMULSIFYING APPARATUS Filed June 20. 1960 3 Sheets-Sheet 3 United States Patent 3,249,340 MIXING AND EMULSIFYING APPARATUS Uherto Pinto, Via Appiani 3, Milan, Italy Filed June 20, 1960, Ser. No. 37,252 Claims priority, application Italy, July 15, 1959,

11,851/59 7 Claims. (Cl. 259-96) This invention relates to apparatus for mixing together two liquid phases, or a solid phase and a liquid phase, to produce an intimately mixed liquid suspension or emulsion. Such apparatus can also of course be used where one phase is more or less soluble in the other. From here on the phases before and during such treatment are spoken of simply as a material to be mixed or emulsified.

The invention more particularly relates to mixing and emulsifying apparatus of the type which can be immersed in material to be mixed in a tank, so that in operation it draws in the material to be mixed, subjects it to a shearing action and passes it back free from swirl or vortex, into the main volume of material with the aid, when necessary, of a deflector plate.

The invention consists in a mixing and emulsifying apparatus in which the inner surface of the impeller housing is frusto-conical and surrounds a bladed, rotary, centrifugal imlpeller with a clearance fi-t, the blades on this impeller having generatrices parallel to the axis of rotation so that in operation material is drawn in axially into a circular inlet at the narrow end of, and passed out between radially'extending non-rotary vanes at the broad end of the housing.

The invention further consists in an apparatus in which the vanes are surrounded by a cylindrical extension of the housing.

The invention relates particularly to a mixing and emulsifying apparatus in which the bladed centrifugal impeller, rota-ting at high speed, is characterised by blades whose gencratices are parallel to the axis of the impeller therefore subjecting the material to a continually increasing centrifugal force by virtue of increasing diameter of the impeller blades and small clearance between the blades and the internal surface of the housing.

Two embodiments of the invention are now described for example only with reference to the accompanying drawings.

FIGURE 1 is a side view of a mixing and emulsifying apparatus with its head suspended in a tank of liquid.

FIGURE 2 is a section on the line 2--2. of FIGURE '1.

FIGURE 3 is a section on the line 3-3 of FIGURE 4.

FIGURE 4 is a section on the line 44 of FIGURE 3.

FIGURES 5 and 6 correspond to FIGURES 3 and 4 and show a modified mixer head which can be substituted for the head of FIGURES 1 to 4. FIGURE 5 is a section on the line 55 of FIGURE 6.

First I will describe the embodiment of FIGURES l to 4 and its method of operation.

The apparatus (as shown in FIGURES 2-4) features a vane assembly denoted by the general reference numeral 4 comprised in the cylindrical upper part of a housing 5, on which this housing is mounted with a pushfit and held against axial and vertical movement by two screws 6. The housing 5 has a frusto-conical lower part open at its narrow end which forms the inlet of the mixer head.

The vane assembly 4 which is in the outlet of the apparatus has a plurality of axially extending vanes 4', of even thickness. Two diametrically opposite vanes 4", or more when necessary, have a thickened portion for receiving one of the screws 6 on the side and in their upper surface threaded bores to receive struts or rods 3; on these struts or rods is mounted the deflector plate as explained more particularly 'below.

3,249,340 Patented May 3, 1966 The central part of the vane assembly 4 forms a plain bearing for a power shaft 1 serving to supply power to the rotary impeller.

The shaft 1 passes into and extends below vane assembly 4 and has fixed to its lower end a rotary impeller, denoted by the general reference numeral 7 by a nut 8. The impeller has a plurality of blades such as 7' of equal thickness which are backwardly curved as regards radial section, that is to say, curved away from their direction of rotation. The vanes 4' and 4" lie in the opposite direction i.e. are curved forwards. The generatrices of the blades 7' and vanes 4' and 4" are parallel to the axis of the impeller.

As can be seen from FIGURE 3, the impeller is of frusto-conical shape and there is a clearance fit between it and the housing 5 and between it and the vanes 4' and 4". At the lower end of the impeller 7, the blades extend below the nut 8 to form exposed surfaces with an open centre and whose inner profile is frusto-conical in the reverse direction to the outer main profile of the impeller.

The mixer head (as shown in FIGURE 1) is connected with an electric motor 16 by the shaft 1 and by the struts or rods 3 so as to form a complete unit. The lower ends of the rods 3, as already said, are tapped and screwed into holes in the vanes 4". The shaft 1 is made in two sections connected together by a threaded sleeve 14, so that its length can be varied for adjustment of the clearance between the impeller 7 and vanes 4. A lock nut 13 is also provided for this, and also for preventing rotation of the lower part of the shaft in relation to the upper part when the mixer is in use. The rods 3 are attached at their upper ends to a coupling flange 15 which is bolted to the motor 16. The whole apparatus is suspended from a wall bracket 18 by means of a wire cable 17 and a counter-weight 9.

A deflector plate 11 having a concave lower surface is slidably mounted on the rods 3 and can be locked in position by a wing bolt 12.

As already indicated, the apparatus is immersed in material to be mixed in a tank 10'.

In operation, the rotation of the impeller 7 at a high speed .by the power shaft 1 causes the material to be sucked in between its blades 7' at their extended lower ends and to be thrust by centrifugal force against the frusto-conical inner surface of the lower part of the housing 5. The material is thus forced upwards out between the non-rotary vanes 4' and the cylindrical upper part of the housing 5. During its passage therethrough, the material is subjected to a considerable shearing action by virtue of the small clearance between the upper edges of the impeller blades 7 and the lower edges of the vanes 4. Therefore the material is halted in its rotary movement and is ejected with great force from between the nonrotary vanes 4' axially and free from vortex up against the lower concave surface of the deflector plate 11 which compels it to flow downwards in a cylindrical stream between the housing 5 and the tank 10, to be drawn again into the mixer head through the inlet at the lower or narrow end of the housing 5. The material is thus maintained in a continuous vertical cycle of movement.

The upper cylindrical part of the housing 5 is thus seen to constitute also a guide for causing the flow from the housing to be axial, cooperating with vanes 4'.

In the head shown in FIGURES 5 and 6 I provide means for adjusting the clearance between the impeller 7 and the vanes 4. To this effect, the vane assembly 4' has an outer concentric ring 4" which is screwed into a female thread in the cylindrical part of the housing 5. The housing can be locked in rotation by means of a screw 6' which can be screwed into any one of a number of radial slots in it. Rotation of the housing 5 about the vane assembly enables the clearance between the inner surface of said housing and the outer profile of the impeller to be altered while the clearance between the impeller and the vanes 4 can be altered by loosening the lock nut 13 and turning the two parts of the shaft in relation to one another.

I find that the slipping of the material along the inner frusto-conical surface of the housing by virtue of the centrifugal force exerted by the impeller 7 and the concomitant shearing action of the upper edges of the blades 7 against the lower side of vanes 4 makes a considerable contribution to the emulsifying action of a mixing apparatus constructed according to my invention.

I also find that a mixer constructed in accordance with the invention has the following advantages:

(1) No air is sucked down from the liquid surface;

(2) There is no bubble formation dueto the shape of the impeller;

(3) It is especially efficient with dense material;

. (4) There is no cavitation-even with dense materials;

' (5) The mechanical efi'iciency is high.

' It should be stressed that my invention is by no means limited to the two embodiments I have illustrated but embraces all the modifications that those skilled in the art can devise without departing from the gist of the invenion as defined in the following claims.

I claim:

1. A mixing and emulsifying apparatus comprising a hollow housing open at opposite ends, said housing having a frusto-conical inner surface converging downwardly, a rotary impeller received in said housing, said impeller comprising a plurality of angularly spaced radially extending blades having their generatrices parallel to the axis of said impeller, substantially the entire length of the outer edges of said .blades conforming to the inner surface of said housing and having a close clearance fit therewith, the spaces between said blades being open along the entire periphery of the impeller and being open at the opposite ends to provide unobstructed axial passages for the axial flow of material through said impeller between said blades and the wider ends of said blades terminating in the same plane, a plurality of angularly space-d radially extending vanes disposed at the wider end of said housing with the radial edges of said vanes adjacent the widerends of said blades spaced therefrom to provide a close working clearance, a shaft fixed to said impeller, and a motor connected to said shaft for driving said impeller, whereby upon immersion of said housing in material to be mixed and rotation of said impeller, said material will flow into the smaller end of said housing, radially into engagement with the inner surface of said housing and axially through said impeller between said blades to be discharged axially from said housing between said vanes, theclearance between the outer edges of said blades and the inner surface of said housing providing a shearing action on said material over substantially the entire axial length of said blades and the. clearance between said vanes and said blades providing a shearing action on said material over substantially the entire radial length of said blades.

2. A mixing and emulsifying apparatus as defined in claim 1 in which said blades are curved away from the direction of rotation of said impeller.

3. A mixing and emulsifying apparatus as defined in claim 1, in which said vanes are curved in the direction of rotation of said impeller.

4. A mixing and emulsifying apparatus as defined in claim 1 in which means is associated with said shaft for adjusting the clearance between said inner surface and the outer edges of said blades and between the radial edges of said vanes and the adjacent radial edges of said blades.

5. A mixing and emulsifying apparatus as defined in claim 4 in which said means comprises means disposed between said motor and impeller for adjusting the length of said shaft, whereby the position of said impeller with respect to said inner surface and said vanes may be adjnsted.

6. A mixing and emulsifying apparatus as defined in claim 1 in which meansis associated with said housing for adjusting the clearance between said inner surface and the outer edges of said blades.

7. A mixing and emulsifying apparatus as defined in claim 6 in which said means comprises screw threads connecting said housing and said vanes, whereby upon rotation of said housing with respect to said vanes the inner surface of said housing will be moved toward or away from the outer edges of said blades.

References Cited by the Examiner UNITED STATES PATENTS 1,795,588 3/1931 Wilson 259- 97 2,267,341 12/1941 Schmidt 259-96 2,421,191 5/1947 Durdin 259-97 2,706,622 4/1955 Staaf 259-96 2,801,083 7/1957 Balassa 25997 2,859,259 11/1958 Stiles 259 FOREIGN PATENTS 777,271 6/ 1957 Great Britain. 547,060 8/1956 Italy.

OTHER, REFERENCES Shear'Flow Industrial Mixers, by Gra-bb Special Products, Inc., Windsor Locks, Conn., Form No. 'RL-lOO 6-59-5M. (Date of publication unknown, received in Patent Oflice 845-63, 2 pages.)

WALTER A. SCHEEL, Primary Examiner.

HERMAN BERMAN, L. I. LEONNIG, J. S. SHANK,

Exa n m 

1. A MIXING AND EMULSIFYING APPARATUS COMPRISING A HOLLOW HOUSING OPEN AT OPPOSITE ENDS, SAID HOUSING HAVING A FRUSTO-CONICAL INNER SURFACE CONVERGING DOWNWARDLY, A ROTARY IMPELLER RECEIVED IN SAID HOUSING, SAID IMPELLER COMPRISING A PLURALITY OF ANGULARLY SPACED RADIALLY EXTENDING BLADES HAVING THEIR GENERATRICES PARALLEL TO THE AXIS OF SAID IMPELLER, SUBSTANTIALLY THE ENTIRE LENGTH OF THE OUTER EDGES OF SAID BLADES CONFORMING TO THE INNER SURFACE OF SAID HOUSING AND HACING A CLOSE CLEARANCE FIT THEREWITH, THE SPACES BETWEEN SAID BLADES BEING OPEN ALONG THE ENTIRE PERIPHERY OF THE IMPELLER AND BEING OPEN AT THE OPPOSITE ENDS TO PROVIDE UNOBSTRUCTED AXIAL PASSAGES FOR THE AXIAL FLOW OF MATERIAL THROUGH SAID IMPELLER BETWEEN SAID BLADES AND THE WIDER ENDS OF SAID BLADES TERMINATING IN THE SAME PLANE, A PLURALITY OF ANGULARLY SPACED RADIALLY EXTENDING VANES DISPOSED AT THE WIDER END OF SAID HOUSING WITH THE RADIAL EDGES OF SAID VANES ADJACENT THE WIDER ENDS OF SAID BLADES SPACED THEREFROM TO PROVIDE A CLOSE WORKING CLEARANCE, A SHAFT FIXED TO SAID IMPELLER, AND A MOTOR CONNECTED TO SAID SHAFT FOR DRIVING SAID IMPELLER, WHEREBY UPON IMMERSION OF SAID HOUSING IN MATERIAL TO BE MIXED AND ROTATION OF SAID IMPELLER, SAID MATERIAL WILL FLOW INTO THE SMALLER END OF SAID HOUSING, RADIALLY INTO ENGAGEMENT WITH THE INNER SURFACE OF SAID HOUSING AND AXIALLY THROUGH SAID IMPELLER BETWEEN SAID BLADES TO BE DISCHARGED AXIALLY FROM SAID HOUSING BETWEEN SAID VANES, THE CLEARANCE BETWEEN THE OUTER EDGES OF SAID BLADES AND THE INNER SURFACE OF SAID HOUSING PROVIDING A SHEARING ACTION ON SAID MATERIAL OVER SUBSTANTIALLY THE ENTIRE AXIAL LENGTH OF SAID BLADES AND THE CLEARANCE BETWEEN SAID VANES AND SAID BLADES PROVIDING A SHEARING ACTION ON SAID MATERIAL OVER SUBSTANTIALLY THE ENTIRE RADIAL LENGTH OF SAID BLADES. 